Evaluation of the ARC Controller for the NASA IRTF Anthony Denault, Charles Lockhart, Eric Warmbier, & John Rayner

Our goal is to answer this question: Does the ARC Gen III array controller satisfy IRTF's needs? Noise Readout speed Reliability Mounting and cabling Schedule Cost Risk

Overview Controller Needs for IRTF The ARC Controller ARC Systems in Use Estimated Performance for IRTF Instruments Controller Mounting & Cabling Issues Tasks, Schedules, & Costs Conclusions

Controller Needs iSHELL o Spectrograph: H2RG, 32 outputs o Guider: Aladdin, 8 output SpeX o Spectrograph: H2RG, 32 output o Guider: Aladdin, 8 outputs NSFCam2: H2RG, 32 outputs

ARC Hardware

ARC Example Configurations

ARC Component Costs

ARC Systems in Use MIRSI uses Gen II Controller o Boards date back to o PCI board very problematic o Briefly considered for iSHELL, NSFCam2, SpeX WIRcam (CFHT) Astronircam (MKIR) o H2RG w/ ARC Gen III controller o 2-3 ADU noise o Estimated gain in e-/ADU=6 o Current fastest pixel time is 3.3 microseconds, rate = 300 kHz

Community Feedback H2RG support is well developed for the ARC controller o Used in all output modes: 1, 4, & 32 o Pixel readout rates used > 300 kHz Stable Operation o Users reported being able to attain stable operation of the controller Read Noise o Users reported that configurations where system noise is device limited were attained.

Measured Performance of the ARC Gain & Noise Testing

Gain Testing: Low Gain Measured system gain: - 24uV/ADU

Gain Testing: High Gain Measured system gain: - 6.2uV/ADU

Noise Testing: Shorted & Grounded Inputs Inputs grounded through 10K resistor Inputs grounded directly Low gain noise: ADU High gain noise: ADU

Measured Performance with Astronircam Test Conditions Cold 85K 4 output mode 3.33 microseconds/pixel Total readout in 3.6s Detector cold blanked off High gain mode

Estimated Performance for IRTF Instruments

IRTF Array Controller Requirements: H2RG

IRTF Array Controller Requirements: Aladdin II/III

Throughput Rate Limitation ** Includes H2RG reference output, essentially a 2048x2112 pixel image Transfer rate using 10 Mpix/s

Summary of H2RG Recommened Readout Rates

Other Gen III ARC Controller Issues Software/system crashes o Occasional failures with Astronircam o After reboot, PCI card needs to be reset o Made fixes to MIRSI PCI driver code to reduce impact of crashes Impact of software/system crash o 3-4 minutes to reboot and restart electronics o Potential problem for occultation programs Long term support o Anticipate vendor support from ARC based on MIRSI experience o Maintain working spares o Use vendor schematics to build replacements if necessary o Status review after 5 years, expect to replace within 10 years

ARC Controller Mounting & Cabling

NSFCam2

SpeX

Current Cabling: NSFCam2

Current Cabling: SpeX

Cabling Questions Cable length o Shorter is better, but how short? ARC Controller Placement Limitations o Cannot mount under NSFCam2 or SpeX o Probably mounted in current locations Cabling Design & Material Connectors o Physically rugged o Minimize number of connectors Forming Cables Cable Exit from ARC Controller o No predetermined exit from controller

Other Cable Designs

Tasks, Schedules, & Costs

Tasks 1. Run Mux/H2RG with current SGIR cabling. 2. Test/Select new NSFCAM2 cabling (Ribbon or Flex Design) 3. Testing and Optimization 4. Start NSFCAM2 update. 5. Run Aladdin MUX with ARC Controller.

Task 1. Run MUX/H2RG with current SGIR Cabling

Task 2 - Test/Select new NSFCAM2 cabling.

Schedule

Executive Summary

Risk Assessment Technical Risks o Noise Performance  Testing indicates ARC controller meets requirements  Very low risk o Throughput performance  ARC controller meets rates specified H2RG controller  Flexibility in throughput requirement  Very low risk o Reliability  System hangs rare event  Problem is likely solvable  Reboot requires 3-5 minutes Management Risks o Ready for NSFCam2 within 6 months o Begin Aladdin customization in 3 months o Other IRTF projects have negative impact

Recommendation We recommend the ARC controller for use at the IRTF for IRTF instruments. Specifically, we recommend using the ARC controller the for building of iShell, and for upgrading SpeX and NSFCam2.